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unexplained issues


CMFG43

New Member
Joined
Sep 27, 2014
Messages
4
Vehicle Year
1989
Transmission
Automatic
hey everyone and thanks in advance for any help. i have a 1989 ranger, 4x4, 2.9l automatic with a strange issue. the truck runs fantastic when you first start it, until it warms up. then shortly after it reaches operating temperature it will start missing and very quickly it will stall and die. sometimes it will start back immediately when cranked but will sputter and die almost instantly. i cannot figure out what is causing this issue but i can give you some history on the truck. less than 1000 miles ago i replaced the head gaskets, before that the truck ran fine. ive replaced the coolant temp sensor, o2 sensor,ignition control module, and fuel pump. when the key is turned over you can hear the pump run, unless it was just cranked and then im guessing the pressure is still holding from before. the relay clicks though every time. the catalytic converter has been cut off so i know it cant be clogging up the exhaust. the problem has gotten more frequent with time. when i first finished the head gaskets i drove the truck to work (almost a 45min drive) with very few issues, most of which i dismissed as the truck having sat around for a while when i was doing the head work. when it runs its almost acts like it has a bit of a vacuum leak but i have checked and rechecked everywhere i can find and capped off everything thats not being used anymore. the only indication of anything i have noticed is that it was getting extremely terrible fuel mileage and that sometimes the oil pressure gauge drops unexpectedly. i believe the sending unit for the gauge is bad since the truck doesnt seem to really act like its starving for oil, but more of a rich fuel condition. im going to try to pull codes on the truck as quickly as i can to see if it sheds any light on whats causing this issue and im going to recheck the timing. but im drawing a blank on what would cause the truck to only have this issue when it warms up. any help would be greatly appreciated.
 
I'd start with the heads. They should be torqued in sequence twice. First time after the new gaskets, second time after the engine is allowed to heat up.
 
Is the 02 sensor grounded properly? A bad 02 ground will keep the computer from seeing the signal, but since it doesn't have a circuit code it will assume the data is can see is valid.

Try unplugging the oxygen sensor and see if the problem does away.
 
what about the ECT & IAT sensor/s??? I had a truck do the same thing and ECT sensor was the cause and IAT settled my idle down.... that was on a 4.9 inline 6 in a f250 though
 

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